Pressure fluid operated tool



Feb. 13, 1934. E H. sHAFF 1,946,548

PRESSURE FLUID OPERATED TOOL Filed 001;. 26, 1931 Patented Feb. 13, 1934 UNTED STATES PATENT oFFicr;

PRESSURE FLUID OPERATED TOOL Application October 26, 1931. Serial No. 571,099

6 Claims.

The invention relates to pressure iiuid operated tools and more particularly to a new and improved portable tool of the hammer type. 1

The primary object of the present invention is to produce a tool of this character embodying novel valve structure of simple and economical form, constructed to produce a tool of minimum overall length capable of rapid and efficient operation.

Another object is to produce a new and improved valve structure for tools of this character arranged so that the parts thereof may be constructed and assembled by a relatively small number of simple manufacturing operations.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing which illustrates a preferred embodiment of the invention.

1n the drawing:

Figure 1 is a central longitudinal sectional view of a pressure fluid operated hammer embodying the features of the invention.

Fig. 2 is an enlarged transverse sectional view of the valve casing taken along the line 2-2 of Fig. 3.

Fig. 3 is an enlarged cross sectional View of the valve casing taken along the line 3-3 of Fig. 2.

Fig. 4.- is an enlarged sectional view taken along the line'4-4 of Fig. 1 to show the manner in which the valve members are held in place.

Fig. 5 is a side elevational view of one of the valve members. Y

In the embodiment'illustrated in the drawing the tool is oi the type generally referred to as a chipping hammer, which comprises an elongated barrel 10 providing a cylinder or piston chamber 11 within which a piston 12 is reciprocable to impact a tool 13 mounted at the forward end of the barrel 10. Screwthreaded on Vthe other or rear end of the barrel 10 is a head 14 which constitutes the handle of the tool and has passages 15 and 16 therein through which pressure :duid is supplied under thecontrol oi a manually operated valve 17. Pressure fluid, after passing the valve 17, is admitted alternately to opposite ends of the cylinder 11 by a suitable valve mechanism mounted at the rear end of the barrel lo and held in place thereon by the head 14. This admission of pressure fluid serves to reciprocate the piston, the exhaust of pressure nuid from the cylinder being controlled by theV piston 12 in its reciprocatory movement.

The preferred form of Valve mechanism comprises an annular valve casing 18 positioned in abutment with the rear end of the barrel 10 within a sleeve 14a formed as an integral part of the head 14 and which surrounds the rear end of the barrel 10 so as to provide the screw threaded connection between the barrel and the head.

Thus the valve casing 18 is held in place on the barrel by the head 14. Preferably the casing 13 is formed from a fiat circular plate having a central bore 19 therein of such size as to form the l rear end of the piston chamber.

The fact that the casing thus provided is relatively thin and serves as a portion of the piston chamber results in a marked reduction in the overall length of the tool.

In the present instance two thin at valve m' members 2c are provided, both mounted in the casing 18 and acting in unison to control the passage of pressure uid to the opposite ends of the cylinder 11. The two valve members 20 are of similar rectangular shape, as shown in Figs. 1 and 5 of the drawing, and are preferably formed from a comparatively thin fiat strip of spring steel. Said valve members 20 are mounted in chambers 21, formed by cutting relatively deep vparallel grooves from the rear side of the casing on opposite sides of the piston chamber. These grooves are of a radial width slightly greater than the thickness of the valve members so as to permit shifting of the valve members alternately into contact with the opposite side surfaces of the 55 chambers.

In their shifting movement, the valve members alternately close opposed radial passages 22 and 23 opening into the valve chambers 21 at opposite sides thereof. The'passages 22 and 23 are preferably formed by a plurality of parallel bores extending substantially radially through the valve casing 18 so as to intersect the chambers 21 at a plurality of points (Fig. 2) spaced longitudinally of lthe valve chambers. Thus the inner ends of the bores constitute the passages 23 which open into the rear piston chamber.

To provide a connection with the front end of the cylinder 11, a passage 25 is formed for each of the valve chambers extending longitudinally ofthe valve casing 18 into communication with the central one of the passages 22. Each of these passages 25 communicates with a longitudinally extending passage 26 formed in the wall of the cylinder. rThe passages 26 are connected to the forward end of the cylinder 11 by means of transverse ports 27. Registry of the passages 25 and 26 is insured by dowels 28 xed in thebarrel 10 and extending into holes 29 (Fig. 2) formed inA the Vvalve casing 18. 1n order to connect all three of Sii the passages 22 with the passage 25, the head 14 within the sleeve 14SL is formed so as to provide an annular space 30 around the outer edge of the valve casing 18.

It will be noted that the valve chambers 2l open through the rear end surface of the valve casing 18 adjacent to the head 14 so that when the head is removed, the valve members 20 may be easily removed edgewise from the valve chambers. To provide for communication between the passage 16 and the valve chambers 21, an annular groove 31 is formed in the head 14 in the surface thereof which engages the rear end surface of the valve member 18 and communicates with the chambers 21 in any rotative positionof the head. The groove 31 is so located Vand'proport'ioned that its edges overlie the ends of the two valve chambers 21 as shown in Fig. 4 of the drawing, whereby to hold the valve members 20 in place in the valve chambers 21.

By this arrangement, the groove 31 is adapted to supply pressure iiuid to the chambers 21 on either side of the valve members 20. Also, it will be seen that the head 14 holds the valve member 18 in place on the barrel l0, that it holds the valves 20 in position within the valve chambers 21, that it provides air supply passages to the valve chambers and between the various outlet passages of the two valve chambers, and that it serves as an end wall for the rear end of the cylinder 11.

The Simplicity of the manufacturing operations involved in producing the present valve mechanism will be apparent from a consideration of Figs. 2 and 3 which show clearly the formation 01' each valve chamber 21 by cutting a straight slotacross the rear face of the valve casing 18 substantially along a chord thereof. This slot in the present instance extends through the side edges of the valve casing and to denne the ends ofthe chamber 21, the two ends of the slot are `plugged as by forming bores 32 at spaced points Aalong the slot and placing plugs 33 therein. This provides a valve chamber of rectangular form so that it is suited for the flat rectangular valve member shown in Fig. 5. It will be noted that Vin the preferred form, the slots whichrprovide the two valve chambers 21 are parallel to each Vother so as to simplify the manufacturing operations involved. Also the bores forming the passages 22 and 23 are parallel to each other and the corresponding passages for the two chambers 21 are formed in alinement with each other.

To provide for exhausting the pressure iiuid from the cylinder 11, a plurality of ports 34 are formed in the wall of the cylinder and are connected to longitudinally extending passages 35. The passages 35 communicate with atmosphere through ports 36 extending through the barrel 10 into a perforated guard 37 of 'conventional construction. The exhaust ports 34 are spaced from the ends of the cylinder 11 so that after the pressure has been exhausted from one end of the cylinder, the return movement of the piston 12 closes the exhaust ports 34 of that end of the cylinder during the terminal portion of the return stroke. This closing of' the exhaust ports causes compression of air in the ends of the cylinders so as to cause shifting of the valve `members 21 in a manner which will be more fully described yin the following outline of the voperation of the tool.

e 'Assuming that the parts are in the position -:shown in Fig. 1, pressure fluid is being admitted from the annual passage 31'through the valve chamber 21, and the passages 23 into the rear end of the cylinder 1l so as to cause forward movement of the piston 12. It will be noted that the piston 12 has covered the forward exhaust ports 34 so that the air trapped in the forward end of the cylinder 11 will be compressed as a forward movement of the piston 12 continues. The pressure thus built up acts through the passages 2'7, 26, 25 and 22 to exert a force upon the valve members 20 tending to shift these members to their inner positions. By reason of the 'passage 30 connecting all of the passages 22, it will be seen that this pressure will be exerted at points spaced longitudinally of the valve members 20. In the continued forward movement o1' the piston 12, the rear exhaust ports 34 are uncovered so that the pressure may be exhausted from the rear end of the cylinder. Since the valves 20 have been shifted as above described, rearward movement of the piston 12 is initiated 95 and after the rear exhaust ports 34 have been covered, the valves are again shifted in the manner above outlined.

I claim as myV invention: l

l. In a pressure iiuid operated hammer having 30() an elongated barrel providing a piston chamber, a valve casing mounted at the rear end of the barrel and having a narrow valve chamber formed therein opening through an outer surface of the plate and positioned substantially perpendicularly M5 with relation to the surface through which it opens, a relatively thin valve member adapted for edgewise'insertion into said valve chamber, vpassages formed in said plate opening into said valve chamber on opposite sides of the valve member 110 and communicating withl opposite ends of -the piston chamber, and a head secured on the barrel and abutting the valve member to hold Vthe same in the chamber, said head having a passage therein arranged to supply pressure-fluid to ythe cham- 11;

Vber on either side of the valve member.

2. A pressure uid operated hammer having 'a wall dening one end of a piston chamber, ahead seciued on the rear end of said wall, -said wall having a narrow slot cut therein forming a valve chamber spaced Vfrom the inner and outer surfaces of the wall and opening edgewise through .the rear end surface of the wall, a thin valve member in said valve chambeigpassageways from opposite sides of said valve chamber to opposite ends 121i of the piston chamber, and a passageway through said head Vforsupplying pressure fluid to-saidvalve chamber.

3. A valve casing for'pressure'fluid operated tools comprising a plateV having a transverse slot formed therein extending partially throughf'the plate from one side thereof, and plugs extending into said slot at points spaced Vlongitudinally thereof to dene the ends of a valve chamber,

land -passages formed in the plate opening -i-nto 135 said chamber on opposite sides thereof.

4. A valve mechanism comprising an annular valve casing adapted to constitute'a continuation of the cylinder of a pressure fluid operated hammer, said casing having a pair of parallel lslots 1210 cut therein on opposite sides of its central opening, plugs positioned'in said slots at spaced points to define a valve chamber inseach of the slots, and said casing having a bore formed therein extending entirely from one side to the other and intersecting both of said slots intermediate said plugs.

5. A valve casing for pressure uid operated hammers comprisinga plate having anarrowslot formed-therein extending; partially throughthe plate from one side thereof, plugs extending into said slot at points spaced longitudinally thereof to define the ends of a valve chamber, and a plurality of passages formed in the plate and intersecting said slot intermediate said plugs so as to provide openings into said chamber on opposite sides thereof at points spaced longitudinally of the chamber.

6. A valve mechanism for pressure fluid operated tools comprising an annular valve casing adapted to constitute a continuation of the cylinder of a pressure fluid operated hammer and 

